NEMA 23, weird velocity results.. need help

As I have previously posted, my motors are running very slow but stable...
slow, I mean somewhere around 10~20mm/sec...

however, when I turned up the velocity say from 10mm/s to 11mm/s...
it will start to vibrate, or just sounds of vibrationg and not moving at all..
then it comes a high pitched, frequency sound...

and i have to hit cancel on LinuxCNC

tried these with the 3 driver boards that came, and also with 3 different motors...
cross-connecting them as I go, so I have tried the same and are true for all 9 so times, as I switched...

I am unsure if this is due to not enough "ground"?
because I am using the controller board GND, which came from the USB-to-PC, and then splicing them to all the 3-driverboards...

I'm unsure if I can just send these GND from driver boards into a big piece of metal?
say... the framework of the CNC? since I made it using metal?

any help here would be very much appreciated...

•3 pcs Nema 23 stepper motor with 425 oz.in,3A
•3 pcs Stepper motor driver DM542A, 24-50VDC, 128 MICSTEPS
•1 pc 350W-36V power supply

its running on half-step, if i remember correctly...
here's the link I posted once, with the settings I'm using...

www.linuxcnc.org/index.php/english/forum...42-step-timespacedir

StepTime 5050ns,
StepSpace 5050ns,
Dir. Hold is 5000ns,
Dir. Setup is 5000ns.

Data from DM542A driver board wave timing diagram.


Velocity is 25mm/s @ accel 150mm/s2
Motor Steps is 200 per rev
Micro step is 4
The same is set on the driver DM542A board 800pulse/rev
DIP @ 5, 7, 8 = ON
DIP @ 1, 2, 3, 4, 6 = OFF

any faster than that, even without load (just the motor sitting on my desk by itself, nothing attached)

the motor will just vibrate and not do anything... which is weird..>.<"

any help will be greatly appreciated

if I'm missing anything or if you need me to post anything for help, please let me know

You could start by posting your configuration files.
The link above did not work for me.
Steppers have a limited rpm range, the results you are getting are normally the results of too high an acceleration or velocity based on the available amps and voltage.
Double check your current and microstepping settings. Try full step and be sure to adjust your scale setting.

Rick G

StepTime 5050ns,
StepSpace 5050ns,
Dir. Hold is 5000ns,
Dir. Setup is 5000ns.

these settings seem way off the mark for a DM542A
what breakout board are you using ?
also post your Hal and INI files as an attachment

you have the stepper drivers set at 800 steps this is quarter step 1/4
these drives start at 400 which is half step

try settings
stepspace 3500
steplen 3500
dirsetup 5000
dirhold 5000

also you should have the + inputs tied to 5v and switching the pulse - and dir - lines on the stepper drives
ground connection should not be a problem as in this configuration it is not used

Hi cncBasher,
let me try the inputs that you have and I'll post my hal & ini in here =)

by the way, i get the issue that when i tightened my motor against the motor "plate" (which I use to secure the motor to the machine frame), the motor seems to not run or jammed...
when I released it from the "plate", and its just the motor, it runs just fine without jammed vibrating..

not sure if this has anything to do with anything? but it did stopped the motor making it hard to turn...
when no electricity is ON (PC off, powersupply to boards OFF), I can hand-turn the motor-shaft, however, its kinda hard to turn them though..

is this normal as well?

will submit tomorrow when I get a chance to test it

when no electricity is ON (PC off, powersupply to boards OFF), I can hand-turn the motor-shaft, however, its kinda hard to turn them though..

A stepper will normally have a somewhat rough feel when turning by hand with the power off as the armature passes the magnets. You will feel it jump form one spot to the next.

Is there a difference in how it feels to turn it by hand with the power off and it it not mounted to the machine and when it is mounted? If so the problem may just be a mechanical binding.



However...

any faster than that, even without load (just the motor sitting on my desk by itself, nothing attached)

the motor will just vibrate and not do anything... which is weird..>.<"

and...

by the way, i get the issue that when i tightened my motor against the motor "plate" (which I use to secure the motor to the machine frame), the motor seems to not run or jammed...
when I released it from the "plate", and its just the motor, it runs just fine without jammed vibrating..

Seem to contradict each other, or are you saying the plate was attached in the earlier post?



Rick G

Juz had the time to run these tests.
Will try rick suggestions turning by hand w power off while attached.
Settings as cncbasher.

Step are inverted.

Update in a bit.

Power off & attaching to housing seems fine.
Turn easy by juz 2 fingers, some resistance, but turnable.
About the same effort as when not attached to the housing.

Now, trying to turn while attached housing and motor to frame, no load.

Attached to the framework and turn by hand feels the same.
2 fingers easy turn with minor resistance.

I try to run at 30mm/s, it runs fine.
However according to linuxcnc I can go up to 173.09mm/s.

What happens now is, anything over the 30mm/s, it will run a few turns and then jammed.

This is where it gets me.
Someone told me the housing might not be strong enough to hold the torque or speed this nema23 is outputing.
Its rated at 425oz/in.

My current setup is at half step, 200pulse/rev, 4 microstep, 1:1 pulley-to-lead, 6.35 lead.

Velocity 30mm/s
Acceleration 800mm/s2

Any ideas as to why any velocity over 30mm/s will turn the motorshaft a few rounds then jammed?

Thanks

Any ideas as to why any velocity over 30mm/s will turn the motorshaft a few rounds then jammed?

The motors are stalling as they cannot achieve the requested speed.
You might want to look here...
www.geckodrive.com/support/step-motor-basics.html
Stepper motor torque can fall off rather quickly as the rpm increase.
What is the voltage and amps of your power supply?

Rick G

you seem to have a number of points worth checking
mechanical binding , although you may have already looked at this , you should not find the stepper is jammed when bolting up to the plate , this suggests that your alignment is not correct
of the shaft to the driven screw , so when you tighten it pulls out of axial alignment , you should be able to turn the motor , say at the coupler using your fingers , with power off and everything bolted tight

you say here : My current setup is at half step, 200pulse/rev, 4 microstep, 1:1 pulley-to-lead, 6.35 lead.
which in term contradicts half step = 400 steps not 4 microsteps , the leadshine stepper drivers start at half step not 200 ( this being full step )
so this will have an impact on your scaling etc

stepper motors work differently to dc motors , coils are energised in the off position ,so holding the position , so being unable to turn when energised is normal and expected
i would also suggest that to start with you use lower acceleration and velocity ,and once everything is running then you can increase , this is usual practice , the point you are experencing of the motors
running and then stopping is usualy the fact that the acceleration cannot be sustained , but this can also be linked to the mechanical binding you are experiencing , so drop the acceleration and look at the mechanical issues first